In studying the neuroregulation of pituitary function we have purified a hypothalamic substance capable of stimulating both immunoreactive (ir-) ACTH and ir-beta-endorphin secretion from rat anterior lobe pituitary cells in vitro. This purified CRF does not stimulate cultures of intermediate ion posterior lobe pituitary cells; however, dopamine inhibits the ir-beta-endorphin secretion from these cells induced by 8 Br-cAMP. A great deal of progress in the past year has been made in the chemical methodology used for isolating and chemically identifying peptides. The use of TEAP and TEAF buffers has greatly increased peptide recovery from reverse phase HPLC systems. Amino acid analysis may now be conducted routinely on a low picomolar scale, and automated sequencing methods have been developed in the low nanomolar range. These combined techniques make possible the isolation of novel biologically active peptides from relatively few fragments of animal tissues. Pigeon pancreatic somatostatin (SS) has been identified using such techniques and shown to be identical to ovine hypothalamic SS. Furthermore, a prohormone form of SS has been demonstrated. Chemically synthesizing analogs of various biologically active peptide has proven useful in understanding and manipulating physiologic events. This past year we have continued our synthesis program for opioid peptides and somatostatin. A novel approach to synthetic peptide analog design is demonstrated by "retro-inverso" enkephalins with enhanced biological activity. New octapeptide SS analogs display increased duration of activity or selectivity in inhibiting glucagon secretion. The development of CNS selective SS analogs has allowed us to study the role of the brain in glucoregulatory physiology.